Champion predictions

Hey all,

I wasn't able to find anything yet regarding strategies on predicting what champs may come your way.

Is there a way to predict? How exactly does the champ deck work?

Sometimes, I will start building a comp, but nothing is coming my way. So, I have to swtich my comp because I'm seeing a lot of this or that. As soon as I switch my comp, i stop seeing those champs. It's depressing as hell, sometimes ;P

Any info would be greatly appreciated, and I apologize if there is a post on this already.